This invention relates to a video display system comprising, a display device for displaying, selectively, pages of information by means of pixels in a static display frame, a display generator for producing, for application to the display device, video signals which pertain to the information of a page selected for display, a display memory for storing, in digital form, the information of a page to be displayed, and a processor for controlling digitally the storage, selection and display of information.
Such a system is known from, for instance, European Patent Application No. 82200241.6 and U.K. Patent Application No. 2 032 740A.
As presently envisaged, the display generator of the system is arranged to produce video signals which are suitable for driving a television monitor. However, the possibility does exist for the information display to be effected using some other form of display device, for instance, a liquid crystal display device. The video signals produced by the display generator would then be appropriate for such an alternative.
The system can be operable to display pages of information in the form of both pictures (graphics) and text, with and without color. For the purposes of the present specification, a page of information will be denoted as either a picture page or a text page depending on whether it is predominately pictorial or textual in context.
A problem that exists with a system of the above character is to provide a suitable index by which the different picture and text pages can be readily identified for selection and display. In a known method of indexing, there is provided a list of items which identify the different pages, this list forming the information of at least one text page which is available for display at the command of a viewer. In general, such a list of items can be composed of an individual title or code number for each page. However, when the number of pages which are available for display is considerable, it may not be possible to identify readily a required page simply by recognition of its title or code number, so that trial and error selection of a page for display may result.